The present invention relates to a grid assembled in a scorotoron charger for charging a component to be charged, and to a scorotoron charger having the grid. The present invention also relates to a process unit including the scorotoron charger and the component to be charged, and to an image forming device incorporating the process unit.
In a conventional image forming device such as a laser printer, a charger, a scanner device, a developing device and image transfer device are provided in order in a rotating direction of a photosensitive drum as a component to be charged by the charger. After the surface of the photosensitive drum is uniformly charged by the charger in accordance with the rotation of the drum, the surface is exposed to scanned high speed laser beam from the scanner device to form an electrostatic latent image on the surface of the drum according to print data. The developing device has a developing roller whose surface is supplied with toners to form a thin toner layer on the surface. Upon rotation of the developing roller, the toner carried on the developing roller is supplied to the surface of the photosensitive drum to form a visible toner image on the surface of the photosensitive drum corresponding to the electrostatic latent image. Then, the visible image carried on the photosensitive drum is transferred onto a sheet when the sheet passes between the photosensitive drum and the image transfer device.
A scorotoron charger having a discharge wire and grid electrodes is used as the charger. Japanese Utility Model Application Kokai No. Hei-2-5764 and Japanese Utility Model Publication No. Sho-60-25068 disclose chargers in which wires are used as the grid electrodes. In the charger disclosed in Japanese Utility Model Application Kokai No. Hei-2-5764, a frame has longitudinal ends each provided with a plurality of upwardly projecting wire latching fingers spaced away from each other by a constant distance. One grid wire having one end fixed to the frame is alternately latched on each finger in a meandering fashion and another end of the grid wire is also fixed to the frame. Thus, a plurality of grid wires are set in parallel with each other. In the charger disclosed in Japanese Utility Model Publication No. Sho-60-25068, a pair of grid plates made from a resilient material are positioned spaced away from each other. Each grid plate is provided with fingers and pawls, whose numbers are equal to the numbers of grid wires. Each end of the grid wire is provided with a knot engaged with the pawls. One end of each wire is secured to each pawl of one grid plate, and other end of the wire is secured to each pawl of other grid plate riding over the fingers. Thus, a plurality of wires are fixed in parallel fashion to the grid plates.
However, in the disclosed chargers, formation of the fingers and pawls is costly, and it would be rather troublesome to latch or fix the wire(s) to the fingers and the pawls.